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How do you wire for 240V - 120/240V on 1 phase S3 type transformer (e.g. EE37S3H)?

Single Phase Transformer Primary and Secondary wiring

Product Line:
LV Transformers

Applies to Energy Efficient (EE) type Transformers by SquareD/Schneider Electric

Transformers are delivered in an unconnected condition, and must be configured for the system need.


Connect a jumper between the H1 and H3 terminals, connect a jumper between the H2 and H4 terminals and bring the 240V in on H1 & H4. Connect a jumper between the X2 and X3 terminals. This will serve as the neutral, and can be bonded to ground, if permitted or required by local code. There will be 240V between X1 and X4 with 120V between X1 and the X2/X3 junction and 120V between X4 and the X2/X3 junction. Again, X2/X3 will be the neutral.  Be sure to check with local Electrical Inspectors or Authority Having Jurisdiction (AHJ) for direction about grounding transformers in your local area.

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